Stackable armchair



FIG. 1 is a front view of a stackable armchair showing my new design;

FIG. 2 is a left side view of the armchair, the right view being a mirror image thereof;

FIG. 3 is a rear view of the armchair;

FIG. 4 is a top view of the armchair; and,

FIG. 5 is a bottom view of the armchair.

FIGS. 4 and 5 have been shown on an enlarged scale with respect to FIGS. 1 through 3. 

The ornamental design for a stackable armchair, as shown and described. 